Can you please give the address of the website?

Also, if you go to the general section of the firefox preferences (type about:preferences#general in the address bar), and uncheck the "open new windows in a new tab instead" option, does it work correctly?

Normally if a pop-up window has a specified size, it will not be diverted to a tab. However, there is a setting to force diversion. Could you check whether you have that set and, if so, go ahead and switch it back? Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste link.o and pause while the list is filtered

(3) In this case, check out setting (B) to two. The others are here for future reference:

(A) browser.link.open_newwindow

3 = divert new window to a new tab (default) (checked*) 2 = allow link to open a new window (unchecked*) 1 = force new window into same tab

* First checkbox in Options > Tabs (Firefox 38: Options > General)

(B) browser.link.open_newwindow.restriction - for links in Firefox tabs

0 = apply the setting under (A) to ALL new windows (even script windows) 2 = apply the setting under (A) to normal windows, but NOT to script windows with features (default) 1 = override the setting under (A) and always use new windows

(C) browser.link.open_newwindow.override.external - for links in other programs

-1 = apply the setting under (A) to external links (default) 3 = open external links in a new tab in the last active window 2 = open external links in a new window 1 = open external links in the last active tab replacing the current page

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Did this ever work in Firefox?

Note that Firefox doesn't support the date and time input elements. See Browser compatibility:

• https://developer.mozilla.org/HTML/element/input

When I go to about:config and search link.o these are my settings. Which ones should I change? browser.link.open_newwindow 3 browser.link.open_newwindow.disabled_in_fullscreen false browser.link.open_newwindow.override.external -1 browser.link.open_newwindow.restriction 2 services.sync.prefs.sync.browser.link.open_newwindow true

What value should I put in each of these? Thanks

Those default settings should work if the date entry window is set to a specific size (you mentioned it was a small window in IE9). As temporary workaround, you could try changing browser.link.open_newwindow to 2, which stops Firefox from diverting new windows to tabs instead to see whether that resolves the issue.

I changed it to 2 and it made no difference. It does say it's a javascript calendar. It still opens in a new tab and not a window.

Let me rewind for a moment. In IE, are you getting a truly separate window or is the pop-up actually an overlay in the same tab?

If it is truly a separate window, could you try disabling the "Adblock Plus Pop-up Addon" in case it is responsible for diverting the new window to a tab? You can do that on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then you should be able to find it on the right side.

Try to set browser.link.open_newwindow.restriction to 1

• http://kb.mozillazine.org/browser.link.open_newwindow.restriction

Hi everyone, You've given me a lot of information to try. I'm going to go through each one tomorrow and it looks like it might take me some time. I'll post my results. In IE 9 when I click on the calendar button it brings up a small window with the month's calendar in it. I click on the date I want, the window closes and the date is entered in the form for my report. The page I'm on is still visible behind the calendar window. When I try it it Firefox 38 it opens another tab and it's full page size and if I click on a date nothing happens. It says it's a javascript calendar. I close the tab and keep trying with no luck. Is there a way I can run debug on the calendar and maybe see where it's failing? I'm not real familiar with programming but am willing to give it a shot. I really don't want to have to use IE anymore as I'm getting real concerned with their security. As far as giving out the website goes - I can't. It's for company use only. Their support says everything on their end is fine. Thanks for all the suggestions and I'll let you know tomorrow.

Also, see if there are any errors.

Open the popup window, click around, do some things you would expect to work but don't, and then right-click and choose "inspect element". Click on the "console" tab, and copy and paste (or take a screenshot of) the messages you see there.

Everyone, Been out for a few days and am in the office today. Everything I tried didn't work but I have made a few discoveries. It seems it is opening a "window" but a size isn't set and in Firefox it looks like a new tab. When I click on the calendar button and open the calendar if I go back to April and click a date, it inserts it in my form. If I click the calendar button again and go to May again and click a date, it inserts the date I need in the form. I have to change the month, click a date, go back in, choose May, click a date and I get what I need. Does this sound more like a javascript problem with Firefox, it is a javascript calendar, or is there something i can tweak? Thanks for all your help so far.

It's difficult to suggest "hacks" without hands-on access to the site...

As a general test, do you still have to use the two-step method if you turn off tabbed browsing? In other words, uncheck the box for "Open new windows in a new tab instead" in Options>General (or in the "old" Options dialog, Options>Tabs).